const http = require('http')
const slice = Array.prototype.slice

class LikeExpress{
    constructor(){
        // 存放中间件
        this.routes = {
            all:[],
            get:[],
            post:[]
        }
    }
    register(path){
        const info = {}
        if(typeof path === 'string'){
            info.path = path
            // 从第二个参数开始，转化为数组 存入stack
            info.stack = slice.call(arguments,1) //数组
        }else{
            info.path = '/'
            // 从第一个参数开始，转化为数组 存入stack
            info.stack = slice.call(arguments,0) //数组
        }
        return info
    }
    use(){
        const info = this.register.apply(this,arguments)
        this.routes.all.push(info)
    }

    get(){
        const info = this.register.apply(this,arguments)
        this.routes.get.push(info)
    }

    post(){
        const info = this.register.apply(this,arguments)
        this.routes.post.push(info)
    }

    match(method,url){
        let stack = []
        if(url === '/favicon.icon'){
            return stack
        }

        // 获取 routes
        let curRoutes = []
        curRoutes = curRoutes.concat(this.routes.all)
        curRoutes = curRoutes.concat(this.routes[method])
        curRoutes.forEach(routeInfo =>{
            if(url.indexOf(routeInfo.path)=== 0){
                // 匹配路由
                //  url === '/api/get-cooke' 且 routeInfo.path === '/'
                stack = stack.concat(routeInfo.stack)
            }
        })
        return stack
    }

    // 核心的 next机制
    handle(req,res,stack){
        const next = ()=>{
            // 拿到第一个匹配的中间件
            const middleware = stack.shift()
            if(middleware) {
                // 执行中间件函数
                middleware(req,res,next)
            }
        }
        next()
    }

    callback(){
        return (req,res)=>{
            res.json = (data)=>{
                res.setHeader('Content-type','application/json')
                res.end(
                    JSON.stringify(data)
                )
            }
            const url = req.url
            const method = req.method.toLowerCase()
            const resultList = this.match(method,url)
            this.handle(req,res,resultList)
        }
    }

    listen(...args){
        const server = http.createServer(this.callback())
        server.listen(...args)
    }

}

// 工厂函数
module.exports = () => {
    return new LikeExpress()
}